During the project period we will investigate the structure and deterioration of semantic memory (i.e., stored knowledge of word and object meaning) and develop an assessment of verbal and nonverbal semantic memory that can be used to stage impairment in dementia. The trainee's long-term goal is to develop and sustain this programmatic line of research as an independent investigator. The K-23 mentored award will foster this goal through a career development plan that emphasizes the following objectives: 1)To advance the trainee's knowledge of neurophysiological and neurobehavioral measurement techniques (e.g., electroencephalography, fMRI); 2) To improve the trainee's knowledge of clinical research design and data analysis; and 3) To improve the trainee's skill in obtaining competitive research funding. The trainee will conduct the bulk of his research at the University of Florida, a major research university whose onsite resources include the McKnight Brain Institute (equipped with 3 Tesla Philips MR Scanner), Shands Hospital (level I trauma center with satellite memory disorders clinics for patient recruiting) and the Brain Rehabilitation Research Center (BRRC) of the Malcom Randall Veterans Affairs Medical Center. In addition to substantial research infrastructure, UF offers an outstanding intellectual community with renowned researchers in cognitive neuroscience and clinical neuropsychology. Primary mentors for the K-23 include Bruce Crosson, Ph.D. and Leslie Gonzalez-Rothi, Ph.D. Additional contributors include Murray Grossman, M.D., Edith Kaan, Ph.D., Wind Cowles, Ph.D., Nadine Martin, Ph.D., and Lori Altmann, Ph.D. Specific aims are as follows: 1) We will assess the neural substrates of concept representation using both spatially sensitive (i.e., fMRI) and temporally sensitive (i.e, ERP) measures in support of a biologically-constrained theory of semantic cognition; 2) We will develop a psychometrically valid measure of semantic memory with test-retest reliability that can be used to stage the intergrity of multiple components of semantic memory in dementia. Components of this battery will include knowledge: a) word meaning; b) perceptual features; c) abstract attributes; d) environmental context; e) associative relationships; and f) object function.